e2fsprogs: Don't try to close an fd which is negative

e2fsprogs: Don't try to close an fd which is negative

These reflect either file descriptors which aren't tested
for failure, or closures of fd's which may have failed.

In setup_tdb(), test for failure of mkstemp and return
without trying to open the file (again).

In reserve_stdio_fds, rather than closing the "extra"
fd == 3 due to the way the loop is written, just
don't go that far by using while (fd <= 2).

In logsave, it forks and retries forever if open fails,
but at least make coverity happy by explicitly not
trying to close a negative file descriptor.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>